Anger, hurt, betrayal, grief, and shame: these are among the emotions felt by many active and former American Roman Catholics about their church. While sobering statistics about the disaffiliation of Catholics from the church have recently received much attention in the academy, the popular press, and Catholic ecclesiastical circles, the personal, spiritual, and theological struggles that mark the process of disaffiliation have often gone un- or under-observed. In this essay, I contend that deconversion – the process of moving from identification and active engagement with Roman Catholicism to disaffiliation and disengagement – is one of the most theologically significant phenomena in contemporary American Roman Catholic life. The essay begins by reviewing the extant academic and pastoral literature on religious disaffiliation and argues that the framework of “deconversion” provides a helpful lens through which to study those who leave Christian churches in general and the Roman Catholic Church in particular. Demonstrating that many scholars have neither adequately engaged Catholic deconversions as a topic of study, nor created space for deconversion as a positive theological trajectory, I then identify several key doctrinal and ecclesiological issues at stake in the practice and study of deconversion. The essay concludes by suggesting directions for future research.